Pothole patchers are designed to repair potholes that have formed in road surfaces by filling the potholes with a mixture of aggregate and hot emulsion. A pothole patcher is commonly mounted on a chassis of a motor vehicle and includes a hopper for storing aggregate, an emulsion tank for storing emulsion, a motor-driven hydraulic pump for blowing forced air, and a boom having a spray nozzle for spraying a mixture of emulsion and aggregate. A conduit or a series of conduits typically extends between the hydraulic pump, the hopper, and the boom. In operation, aggregate drops from the hopper into the conduit, where forced air provided by the hydraulic pump entrains and carries the aggregate to the boom. The aggregate is mixed with emulsion in the boom and the spray nozzle sprays the mixture of emulsion and aggregate into a pothole.
In some known pothole patchers, the hopper is pressurized to help aggregate move down through the hopper, out through a bottom outlet of the hopper, and into the conduit. Pressurizing the hopper prevents aggregate from clogging the bottom outlet of the hopper and facilitates a steady flow of aggregate into the conduit. However, pressurizing the hopper requires a hopper design and additional components that are expensive and subject to failure.
For example, oftentimes a gasket is provided between a lid and a top rim of the hopper to seal the hopper and thereby enable pressurization. This gasket wears over time and becomes less efficient, and may eventually require replacement. In some cases, when the lid is closed, aggregate may get trapped on the gasket, between the lid and the top rim of the hopper. The trapped aggregate accelerates wear of the gasket. What's more, to pressurize the hopper, forced air is sometimes routed from the hydraulic pump to the inside of the sealed hopper and thereby puts additional load on the motor-driven hydraulic pump, which, in addition to wearing the pump, requires additional fuel and thereby increases the overall cost of repairing potholes. To withstand pressurization, the hopper must be constructed of heavy duty components. However, even when constructed of heavy duty components, hoppers are subject to failure when pressurized. Failure due to pressurization may be dangerous. For example, an explosion-like failure may propel components away from the hopper at high rates of speed. The propelled components may cause injury or damage property.
In other known pothole patchers, an auger or screw conveyor is provided in the hopper for guiding aggregate down the hopper and pushing aggregate through the bottom outlet and into the conduit. Augers and screw conveyors are rotating implements powered by hydraulic motors. Further, in other known pothole patchers, a vibrator is provided on or within the hopper to agitate the aggregate to prevent the aggregate from amalgamating and sticking to the inner walls of the hopper and to facilitate flow of aggregate down the hopper and out through the bottom outlet. However, like pressurizing the hopper, installing an auger, a screw conveyer, and/or a vibrator requires additional components, including moving components that are subject to failure and that are expensive to repair and maintain. Further, a hopper equipped with an auger, a screw convey, and/or a vibrator is still subject to clogging. For example, aggregate in the hopper could jam the rotating auger or screw conveyor and thereby clog the hopper and prevent aggregate from dropping in to the conduit. In this event, because the auger is not easily accessible, an operator may be tempted to climb into the hopper and attempt to free the auger or screw conveyor. However, climbing into the hopper is dangerous because the auger or screw conveyor may resume operation while the operator is still in the hopper.
Also, in some known pothole patchers, to control movement of the boom and delivery of emulsion and aggregate, operators must use both hands to flip switches and depress buttons on separate consoles. Further, in some cases, operators must exit the operator cabin to access various controls mounted along the chassis of the vehicle. For example, the operator may have to exit the operator cabin to access controls that control the speed of the motor-driven hydraulic pump, the pressure inside of the emulsion tank and/or hopper, the position of valves that permit and block the flow of emulsion and aggregate, and the position of the boom.